1. Field of the Invention
The invention relates generally to audiovisual transmission quality measurement and, more particularly, to a device and method for estimating subjective audiovisual quality impairment due to transmission impairments, such as packet loss and jitter, in frame-based multimedia transmission networks.
2. Description of the Related Art
It is a long-standing problem in psychology to discover objective, numerical metrics which can be used to predict subjective or human experiences of audiovisual quality. Examples of objective metrics in the field of audio measurement include signal-to-noise ratio, signal level or loudness, transmission delay, and loudspeaker frequency response. Human perceptions of audiovisual quality are typically probed using psychometric methods such as Mean Opinion Score (MOS) tests, in which panels of listeners are exposed to a series of audio samples and asked to rate the quality of the samples on a five-point scale (1=poor, 5=excellent). By this method and by averaging the responses of many human subjects, various conditions can be ranked numerically. However, such tests are costly, time-consuming, and require human subjects. Hence, such tests are not suited to real-time applications such as monitoring the “health” of a telecommunications network servicing thousands of simultaneous telephone calls.
There is a need to monitor or predict the “user quality experience” in a variety of telecommunications systems via automatic processes in real-time, in which the ultimate receiver is a human perceiving an audio or video signal. Therefore, an estimate or prediction of a subjective, human response (such as the voice quality MOS score discussed above) based on objective, numerical information sources which are available or observable is desirable.